Spectral-efficiency optimization for NOMA-based amplify-and-forward cooperative relaying systems with beamforming and power allocation

• Published in: Wireless networks Vol. 27; no. 6; pp. 4123 - 4132
• Main Authors: Yang, Kai, Yan, Xiao, Wang, Qian, Wu, Hsiao-Chun, Qin, Kaiyu
• Format: Journal Article
• Language: English
• Published: New York Springer US 01.08.2021; Springer Nature B.V
• Subjects: Beamforming; Communications Engineering; Computer Communication Networks; Convexity; Electrical Engineering; Engineering; IT in Business; Monte Carlo simulation; Networks; Nonorthogonal multiple access; Optimization; Original Paper; Relaying; Wireless networks; Spectrum-efficiency (SE); Weighted-sum-minimum mean-squared-error (WSMMSE); Power allocation (PA); Relay beamforming-matrix (BM); Non-orthogonal multiple-access (NOMA)
• ISSN: 1022-0038; 1572-8196
• DOI: 10.1007/s11276-021-02733-9

In this paper, we propose a novel spectrum-efficiency (SE) optimization scheme for amplify-and-forward (AF) cooperative relaying systems based on non-orthogonal multiple-access (NOMA). In this network, a weighted-sum-minimum mean-squared-error (WSMMSE) method is utilized to transform the original non-convex optimization problem into a tractable optimization problem. Then, the relay beamforming-matrix (BM) and the power-allocation (PA) coefficients are alternately optimized by use of the iterative beamforming method and the Lagrange-multiplier (LM) method subject to the quality-of-service requirements. Monte Carlo simulation results verify that our proposed new scheme can attain better performance than the optimal PA-NOMA technique and the conventional orthogonal multiple-access (OMA) technique.